Martingale-Based Space-Air-Ground Integrated Network Latency Violation Boundary and Reliability Analysis

SAGIN realizes seamless 6G coverage and highly reliable ubiquitous connectivity via multi-dimensional collaboration. However, the analysis of multi-node latency based on static assumptions fails to reflect the dynamic variations in service. Also, link latency estimation methods don’t adequately consider the dominant effect of bottleneck nodes in multi-node cascades, leading to deviations in latency upper boundary. This paper presents a martingale-based analytical method, it is designed to evaluate the latency violation bounds of multi-node downlink in SAGIN and analyze its reliability. Firstly, we formulate the arrival and service processes of multi-node links, based on the transmission characteristics of SAGIN. Secondly, we construct a joint martingale for arrivals and services, and rigorously derive the latency violation boundary. Finally, we analyze the reliability of downlink flow through latency violation rate assessment. Through simulation of node arrival and service processes in the downlink of SAGIN, we validate the correctness of the latency violation boundary. Simulation results validate the effectiveness of the proposed method, demonstrate its capability in tightly displaying latency boundary, and provide a solid theoretical foundation for further link reliability assessment.